Tracking And Data Relay Satellite System Research Articles

Comprehensive Evaluation on Space Information Network Demonstration Platform Based on Tracking and Data Relay Satellite System.

Due to the global coverage and real-time access advantages of the Tracking and Data Relay Satellite System (TDRSS), the demonstration platform based on TDRSS can satisfy the new technology verification and demonstration needs of the space information network (evolution from sensorweb). However, the comprehensive evaluation research of this demonstration platform faces many problems: complicated and diverse technical indicators in various areas, coupling redundancy between indicators, difficulty in establishing the number of indicator system layers, and evaluation errors causing by subjective scoring. Concerning the difficulties, this paper gives a method to construct this special index system, and improves the consistency of evaluation results with Analytic Hierarchy Process in Group Decision-Making (AHP-GDM). A comprehensive evaluation index system including five criterions, 11 elements, more than 30 indicators is constructed according to the three-step strategy of initial set classification, hierarchical optimization, and de-redundancy. For the inconsistent scoring of AHP-GDM, a high-speed convergence consistency improvement strategy is proposed in this paper. Moreover, a method for generating a comprehensive judgment matrix (the aggregation of each judgment matrix) aggregation coefficient is provided. Numerical experiments show that this strategy effectively improves the consistency of the comprehensive judgment matrix. Finally, taking the evaluation of TDRSS development as an example, the versatility and feasibility of the new evaluation strategy are demonstrated.

Serially concatenated extended CPM scheme based on TDRSS

Tracking and Data Relay Satellite System (TDRSS) can meet the needs of Low EarthOrbit (LEO) satellite real-time transmission, but it also has large Doppler shift, transmission delay and channel fading. Continuous Phase Modulation (CPM), with excellent properties of both bandwidth and energy efficient, are very suitable for nonlinear and/or fading channels such as satellite channel due to the constant envelope nature. In this paper, the CPE in the SCCPM scheme is replaced by the designed ECE to construct a new scheme called SCECPM scheme, in order to enhance the robustness of the signal. Compared with previous SCCPM scheme, the proposed system shows an improvement concerning the convergence threshold and bit-error-rate (BER).

Space VLBI: from first ideas to operational missions

The operational period of the first generation of dedicated Space VLBI (SVLBI) missions commenced in 1997 with the launch of the Japan-led mission VSOP/HALCA and is coming to closure in 2019 with the completion of in-flight operations of the Russia-led mission RadioAstron. They were preceded by the SVLBI demonstration experiment with the Tracking and Data Relay Satellite System (TDRSS) in 1986–1988. While the comprehensive lessons learned from the first demonstration experiment and two dedicated SVLBI missions are still awaiting thorough attention, several preliminary conclusions can be made. This paper addresses some issues of implementation of these missions as they progressed over four decades from the original SVLBI concepts to the operational status.

Dynamic Relay Satellite Scheduling Based on ABC-TOPSIS Algorithm

Tracking and Data Relay Satellite System (TDRSS) is a space-based telemetry, tracking, and command system, which represents a research field of the international communication. The issue of the dynamic relay satellite scheduling, which focuses on assigning time resource to user tasks, has been an important concern in the TDRSS system. In this paper, the focus of study is on the dynamic relay satellite scheduling, whose detailed process consists of two steps: the initial relay satellite scheduling and the selection of dynamic scheduling schemes. To solve the dynamic scheduling problem, a new scheduling algorithm ABC-TOPSIS is proposed, which combines artificial bee colony (ABC) and technique for order preference by similarity to ideal solution (TOPSIS). The artificial bee colony algorithm is performed to solve the initial relay satellite scheduling. In addition, the technique for order preference by similarity to ideal solution is adopted for the selection of dynamic scheduling schemes. Plenty of simulation results are presented. The simulation results demonstrate that the proposed method provides better performance in solving the dynamic relay satellite scheduling problem in the TDRSS system.

Adaptive subsequence adjustment with evolutionary asymmetric path-relinking for TDRSS scheduling

Due to the limited transmission resources for data relay in the tracking and data relay satellite system (TDRSS), there are many job requirements in busy days which will be discarded in the conventional job scheduling model. Therefore, the improvement of scheduling efficiency in the TDRSS can not only help to increase the resource utilities, but also to reduce the scheduling failure ratio. A model of nonhomogeneous parallel machines scheduling problems with time window (NPM-TW) is firstly built up for the TDRSS, considering the distinct features of the variable preparation time and the nonhomogeneous transmission rates for different types of antennas on each tracking and data relay satellite (TDRS). Then, an adaptive subsequence adjustment (ASA) framework with evolutionary asymmetric path-relinking (EvAPR) is proposed to solve this problem, in which an asymmetric progressive crossover operation is involved to overcome the local optima by the conventional job inserting methods. The numerical results show that, compared with the classical greedy randomized adaptive search procedure (GRASP) algorithm, the scheduling failure ratio of jobs can be reduced over 11% on average by the proposed ASA with EvAPR.

A hybrid multiuser detector based on MMSE and AFSA for TDRS system forward link.

This study mainly focuses on multiuser detection in tracking and data relay satellite (TDRS) system forward link. Minimum mean square error (MMSE) is a low complexity multiuser detection method, but MMSE detector cannot achieve satisfactory bit error ratio and near-far resistance, whereas artificial fish swarm algorithm (AFSA) is expert in optimization and it can realize the global convergence efficiently. Therefore, a hybrid multiuser detector based on MMSE and AFSA (MMSE-AFSA) is proposed in this paper. The result of MMSE and its modified formations are used as the initial values of artificial fishes to accelerate the speed of global convergence and reduce the iteration times for AFSA. The simulation results show that the bit error ratio and near-far resistance performances of the proposed detector are much better, compared with MF, DEC, and MMSE, and are quite close to OMD. Furthermore, the proposed MMSE-AFSA detector also has a large system capacity.

Reliability Growth Analysis of Satellite Systems


 
 
 A reliability trend/growth analysis methodology for satellite systems is suggested. A satellite system usually consists of many satellites successively launched over many years, and its satellites typically belong to different satellite generations. This paper suggests an approach to reliability trend/growth data analysis for the satellite systems based on grouped data and the Power Law (Crow-AMSAA) Non- Homogeneous Poisson process model, for both one (time) and two (time and generation) variables. Based on the data specifics, the maximum likelihood estimates for the Power Law model parameters are obtained. In addition, the Cumulative Intensity Function (CIF) of a family of satellite systems was analyzed to assess its similarity to that of a repairable system. The suggested approaches are illustrated by a case study based on Tracking and Data Relay Satellite System (TDRSS) and Geostationary Operational Environmental Satellite (GOES) data.
 
 

Space-Based TTC Method of Lower Orbit Satellite

我国的航天器测控主要依赖地基测控系统实施,随着民用和军用需求的不断增加,太空运行的低轨航天器数量越来越多.仅依赖地基测控系统满足这些航天器的测控需求越来越困难,费用也越来越高.探索新的、有效且经济的测控模式势在必行.天基测控技术是航天器测控发展的方向,研究和应用天基测控技术具有重要的实用价值,可以解决困扰我国航天领域多年的测控资源紧张问题.在分析美国NASA数据与中继卫星系统相关技术的基础上,提出了我国低轨航天器天地基测控模式,讨论了该模式的运行原理,设计了该模式的仿真系统,分析了应用该模式需解决的关键技术问题,通过基于设计的仿真系统对提出的测控模式进行了验证.验证结果表明了提出的天地基测控模式可行,可以满足低轨航天器的测控需求.

Real time science displays for the PCA experiment on the Rossi X-ray Timing Explorer

The Rossi X-ray Timing Explorer (RXTE) spacecraft was launched on 30th December 1995 and contains a large Proportional Counter Array (PCA) experiment developed at GSFC. Telemetry from RXTE is returned via the NASA Tracking and Data Relay Satellite System (TDRSS) which, apart from specific gaps in coverage, provides a steady stream of nearly continuous real time data packets. The PCA has an area of 7000 cm 2 and produces high count rates for many x-ray sources. This provides the opportunity for some serious interpretation and decision making in real time. The display programs developed by the PCA team fall into 4 classes: Housekeeping, General performance (Instrumental and calibration bias), Spectral (Science bias) and Temporal (Science bias). These displays are used by the duty scientist and experiment controllers to monitor the observation in progress to try and ensure that the observation is proceeding as planned and that modifications to the observing modes are not required. Guest Observers (GO's) can be present in the Science Operations Facility (SOF) for their observations. The PCA team can also monitor their experiment using these programs. The SOF are planning to make some or all of these display tools available to GO's at their home institutions for the specific duration of their observations. This paper briefly describes the available display options.

Space Shuttle Precision Orbit Determination in Support of SLA-1 Using TDRSS and GPS Tracking Data

On January 11, 1996, the Space Shuttle Endeavor, mission STS-72, was launched, carrying aboard the first of four Shuttle Laser Altimeter (SLA) experiments. In support of SLA-1, precise orbits have been computed from Tracking and Data Relay Satellite System (TDRSS) Doppler observations. In some cases, these data were combined with Global Positioning System (GPS) pseudorange observations. Traditionally, the Tracking and Data Relay Satellite (TDRS) orbits themselves have been the dominant source of error in Shuttle orbit determination during quiescent attitude periods. However, a new technique utilizing TOPEX/Poseidon’s (T/P) precise orbit knowledge plus the TDRSS-T/P Doppler tracking is used to significantly reduce the TDRS orbit errors. That approach, along with improved modeling and parameterization have allowed us to compute precise Shuttle orbits from TDRSS-Shuttle Doppler tracking data. Orbit overlap comparisons indicate these Doppler-derived orbits have a meter level (1σ) radial precision, and they agree radially with the combined Doppler and GPS derived orbits at the 1.5 m level (1σ).

Orbit determination of TOPEX/POSEIDON and TDRSS satellites using TDRSS and BRTS tracking

TOPEX/POSEIDON (TP) orbits were computed from measurements taken by the US Tracking and Data Relay Satellite (TDRS) System (TDRSS). TP orbits can be computed from TDRSS tracking with an accuracy on the order of 10 cm in the radial direction and 20 cm in absolute position if the orbits of the TDRSs are known with high accuracy. Orbits of TDRSs can be determined with an estimated accuracy significantly better than 10 m in the radial direction, and 20 m in absolute position, if the high-accuracy TP orbits from SLR/DORIS tracking are used as constraints in orbit computations of the TDRSs, and use is made of TP tracking data by TDRSS. If the orbits of TP and the TDRSs are estimated together from both TDRSS tracking data and data acquired by the Bilateration Ranging Transponder (BRT) System (BRTS) and no a priori information is used, these accuracy levels are 25 cm and 2–5 m for TP, and 10 m and 20–30 m for the TDRSs, respectively. Orbits of the TDRSs can be computed with an accuracy of 10 m in the radial direction and 30–40 m in absolute position if only BRTS tracking data is used. Finally, maneuvers of TDRSs and TP have been estimated with high accuracy from BRTS and TDRSS tracking data.

Overview of TDRSS

The National Aeronautics and Space Administration (NASA) has developed the Tracking and Data Relay Satellite (TDRS) System (TDRSS) for operational tracking and communications support of low Earth-orbiting satellites. TDRSS currently consists of five geosynchronous spacecraft and the White Sands Complex (WSC) at White Sands, New Mexico. The Bilateration Ranging Transponder (BRT) System (BRTS) supports range and Doppler measurements for each TDRS using standard user tracking services. These measurements are used to generate well-determined ephemerides for the TDRSs. TDRSS provides S-band and Ku-band services through the single access (SA) antennas and S-band services through the S-band multiple access (SMA) phased array. TDRSS is capable of supporting coherent range and two-way Doppler tracking as well as noncoherent one-way return-link and one-way forward-link Doppler tracking of user spacecraft. Accurate one-way return-link tracking, which can use SMA, the most available TDRSS resource, requires a stable oscillator onboard the user spacecraft as the source of frequency. Two-way and one-way return-link tracking measurements are used for ground orbit determination for navigation and precise positioning; one-way forward-link tracking is used for autonomous onboard navigation with achievable accuracies better than those of the Global Positioning System (GPS) Precise Positioning System (PPS). This overview will discuss the various tracking and navigation capabilities of TDRSS, as well as many of the operational and research applications that have been conducted for missions such as Landsat-4, Ocean Topography Experiment (TOPEX)/Poseidon (T/P), Cosmic Background Explorer (COBE), and Extreme Ultraviolet Explorer (EUVE).

Precision orbit determination for TOPEX/Poseidon using TDRSS doppler tracking data

Precision orbit determination on the TOPEX/Poseidon (T/P) altimeter satellite is now being routinely achieved with sub-5cm radial and sub-15 cm total positioning accuracy using state-of-the-art modeling with precision tracking provided by a combination of: (a) global Satellite Laser Ranging (SLR) and Doppler Orbitography and Radiopositioning Integrated by Satellite (DORIS), or (b) the Global Positioning System (GPS) Constellation which provides pseudo-range and carrier phase observations. The geostationary Tracking and Data Relay Satellite System (TDRSS) satellites are providing the operational tracking and communication support for this mission. The TDRSS Doppler data are of high precision (0.3 mm/s nominal noise levels). Unlike other satellite missions supported operationally by TDRSS, T/P has high quality independent tracking which enables absolute orbit accuracy assessments. In addition, the T/P satellite provides extensive geometry for positioning a satellite at geostationary altitude, and thus the TDRSS-T/P data provides an excellent means for determining the TDRS orbits. Arc lengths of 7 and 10 days with varying degrees of T/P spacecraft attitude complexity are studied. Sub-meter T/P total positioning error is achieved when using the TDRSS range-rate data, with radial orbit errors of 10.6 cm and 15.5 cm RMS for the two arcs studied. Current limitations in the TDRSS precision orbit determination capability include mismodeling of numerous TDRSS satellite-specific dynamic and electronic effects, and in the inadequate treatment of the propagation delay and bending arising from the wet troposphere and ionosphere.

Landsat-4 orbit determination using TDRSS

This paper presents the results of a study to compare the orbit determination accuracy for a Tracking and Data Relay Satellite (TDRS) System (TDRSS)-user spacecraft, Landsat-4, obtained using a Prototype Filter Smoother (PFS), with the accuracy of an established batch-least-squares system, the Goddard Trajectory Determination System (GTDS). The results of Landsat-4 orbit determination provide useful experience for the Earth Observing System (EOS) series of satellites. The filtered and smoothed PFS orbit solutions were compared with the definitive GTDS orbit solutions for Landsat-4; the root-mean-square (RMS) solution difference was 6.6 meters.

Autonomous navigation using the TDRSS Onboard Navigation System (TONS)

The National Aeronautics and Space Administration (NASA) Goddard Space Flight Center (GSFC) is currently developing a Tracking and Data Relay Satellite (TDRS) System (TDRSS) Onboard Navigation System (TONS) to provide onboard knowledge of highly accurate navigation products autonomously to users of TDRSS. The TONS I operational system processes Doppler data derived from scheduled forward-link S-band services to provide onboard orbit and frequency determination and time maintenance. TONS I is implemented using a stable onboard frequency reference, a Doppler measurement capability in the user transponder, and onboard navigation/signal acquisition software. The success of the TONS experiment (1992/1993), which was implemented on the Explorer Platform/Extreme Ultraviolet Explorer (EP/EUVE) spacecraft, demonstrated the flight readiness of TONS I. TONS II-A provides the user with additional Doppler data derived from an S-band beacon signal, available approximately 80 percent of the time. This paper describes the TONS operational capabilities, configurations, and expected performance.

Accuracy assessment of TDRSS-based TOPEX/Poseidon orbit determination

Orbit determination results are obtained for the Ocean Topography Experiment (TOPEX)/Poseidon spacecraft by the Goddard Space Flight Center (GSFC) Flight Dynamics Division (FDD) using a batch-least-squares estimator available in the Goddard Trajector Determination System (GTDS) to process Tracking and Data Relay Satellite (TDRS) System (TDRSS) measurements. The GTDS orbit solutions are compared with the definitive Precision Orbit Determination (POD) orbit solutions. The root-mean-square (RMS) solution difference in the radial component is 28 centimeters.

Communications support for lunar missions using the TDRS II system

The United States National Aeronautics and Space Administration's (NASA's) Office of Exploration (OEXP) is evaluating potential scenarios for robotic and piloted missions to the Moon. This work is part of the OEXP effort to establish a human exploration program during the next century. For more than 4 years, NASA's Goddard Space Flight Center (GSFC) has been performing systems engineering analysis for lunar exploration scenarios. The GSFC studies have focused primarily on lunar communications, data systems, and operations. Two basic Earth-region communications architectures have been identified and seriously considered: ground terminal architectures, such as the Deep Space Network, and geosynchronous relay satellite architectures, such as the Tracking and Data Relay Satellite II (TDRS II). The TDRS II, as currently specified, is a viable architecture and low-cost option - at least for early (1998 - 2005) lunar mission phases. Development of TDRS II, designed as a follow-on to the currently operating Tracking and Data Relay Satellite System (TDRSS), is scheduled to begin soon. A major benefit of the TDRS II option is that the system as planned can provide substantial support to early lunar missions without modification.

Interference effects on Space Station Freedom and Space Shuttle orbiter Ku-band downlinks

The Space Shuttle orbiter (SSO) Ku-band single access return (KSAR) link and the Space Station Freedom (SSF) KSAR link via the tracking and data relay satellite system (TDRSS) use the same carrier frequency. The interference between spacecraft is minimized by opposite antenna polarizations and by TDRSS antenna beam pointing, but if the SSF and SSO are in close proximity, it is expected that mutual interference will be significant. It is shown that a simplified analytical approach will yield adequate accuracy for the expected range of operating conditions. Relative degradation in bit-energy-to-thermal-noise power spectral density ratio to achieve a 10/sup -5/ coded bit-error probability is determined to be 4 dB for the Ku-band SSO-to-TDRS I-channel return link with a 4.5-dB effective signal-to-interference total power ratio (S/I) when the Ku-band SSF-to-TDRS return link interferes. For the Ku-band SSF-to-TDRS return link, both analysis and simulation results yield a relative signal degradation of 0.4 dB at the effective S/I=21.6 dB.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

44. Astronomy from Space L’Astronomie à Partir de L’Espace

The 1987-90 triennium has been a prosperous one for space astronomy. The field has benefited from diverse activities, ranging in style from the continued operation of some old instruments, such as uv spectrographs aboard IUE and Voyager, to the introduction of completely new observing techniques, such as the Hipparcos mission to perform astrometry over large angles and the radio Very Long Baseline Interferometry (VLBI) demonstration with the NASA’s Tracking and Data Relay Satellite System (TDRSS). We have witnessed some important highlights in space astronomy which significantly enhanced our understanding of some fundamental problems in astrophysics. For instance, the COBE satellite offered a tremendous gain in the precision of measuring the cosmic background radiation, and initial results seem to authenticate the simple character of this microwave radiation. As noted in the previous report of Commission 44, Supernova 1987A in the Large Magellanic Cloud was the brightest supernova since the one sighted by Kepler in 1604. There have been remarkable improvements in astronomical instruments since Kepler’s time, and the fruits of our good fortunes with 1987A are now appearing in the literature. Finally, the long anticipated launch of our biggest enterprise in space astronomy, the Hubble Space Telescope, occurred in the spring of 1990.

The European data relay system: present concept and future evolution

After briefly reviewing the users' requirements and the results of traffic scenario simulations needed to size the system, the design of the European data relay system (DRS) (ground and space segment) is presented in detail. The interrelationship with the other data relay systems (NASA's tracking and data relay satellite system (TDRSS) And the Japanese data relay and tracking satellite system (DRTSS)) is discussed together with the current status of systems interoperability. The evolution of DRS into a second generation, foreseen for operation at the beginning of next century, is outlined in terms of user scenario, improved spacecraft and system configurations, and technology developments needed. >